<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .outer {
        width: 400px;
        height: 400px;
        border: 1px solid #000;
      }
      .box {
        width: 100px;
        height: 100px;
        background-color: pink;
        margin: 80px;
      }
    </style>
  </head>
  <body>
    <div class="outer">
      <div class="box"></div>
    </div>
    <script>
      const oOuter = document.querySelector(".outer");
      const oBox = document.querySelector(".box");

      oOuter.onclick = function (e) {
        console.log(e.offsetX);
      };
    </script>
     <style>
      .outer {
        width: 400px;
        height: 400px;
        border: 1px solid #000;
      }
      .box {
        width: 100px;
        height: 100px;
        background-color: pink;
        margin: 80px;
      }
    </style>
  </body>
</html>
